1907.] Influence of Increased Barometric Pressure on Man. 13 
_ Table I. 
Number of men taken - 
ill whose ages are 
Number of men examined Proportion of illnesses to 
Ages. 
and passed. necawded: every 100 men passed. 
15—20 55 0 0 
20—25 145 15 10°3 
25—30 152 37 24 °3 
30—35 91 19 20 °9 
35—40 61 14 22 °9 
40—45 38 10 26 °3 
45—50 3 5 166-0 
Totals... 545 100 
Supposing, however, that the men examined by Snell were a fair sample of 
- the workers, they can be used as a, measure of the age distribution in the whole 
class of employés. If there be no special liability to illness at any particular 
age, the number of men of a given age who suffer should be simply n’ PINS 
total number of cases, where N = 545, n’ the number of men within the 
specified age limits as recorded above. In this way we obtain the subjoined 
table :— 
| Table II. 
| Ages. Actuai number affected. Theoretical number, 
Applying the usual test for goodness of fit (4) to this distribution, y? is 
found to be 56°44, so that the odds are more than a million to one against 
a worse agreement between theory and observation if the deviations are 
merely a result of random sampling. 
In the same way, if we group the 143 cases with recorded ages given by 
v. Schrotter (2), from the Niissdorf Works, and assume Snell’s age distribution 
to hold for these works (a not very improbable assumption, since we know 
that many caissoniers travel from place to place through England and 
Kurope), we have :— | 
